Preliminary Results from Integrating Compton Photon Polarimetry in Hall A of Jefferson Lab

TL;DR

This paper reports on the development and initial testing of a Compton polarimeter for precise, continuous electron beam polarization measurements at Jefferson Lab's Hall A, aiming for 1% statistical accuracy within two hours.

Contribution

It introduces an upgraded Compton polarimeter system and presents preliminary results across various beam energies and photon rates.

Findings

Achieved initial polarization measurements with 1% statistical accuracy goal.

Demonstrated system performance at beam energies from 3.5 to 5.9 GeV.

Validated the non-invasive, continuous measurement capability.

Abstract

A wide range of nucleon and nuclear structure experiments in Jefferson Lab's Hall A require precise, continuous measurements of the polarization of the electron beam. In our Compton polarimeter, electrons are scattered off photons in a Fabry-Perot cavity; by measuring an asymmetry in the integrated signal of the scattered photons detected in a GSO crystal, we can make non-invasive, continuous measurements of the beam polarization. Our goal is to achieve 1% statistical error within two hours of running. We discuss the design and commissioning of an upgrade to this apparatus, and report preliminary results for experiments conducted at beam energies from 3.5 to 5.9 GeV and photon rates from 5 to 100 kHz.